The invention relates to an arrangement for testing metal-clad, high-voltage installations, particularly for detecting partial discharges, in which the metal encapsulation serves at the same time as shielding. An arrangement of this type is disclosed in Deutsche Auslegeschrift No. 1,591,853. The detection and measurement of partial discharges are important particularly in switching installations which are filled with an insulating gas, for example, sulfur hexafluoride, as this permits conclusions to be made as to the freedom from defects and the operational safety of the installation.